I. ˈlō-(ˌ)kō adverb or adjective
Etymology: Italian dialect, there, from Latin in loco in the place
Date: circa 1801
: in the register as written — used as a direction in music
II. noun
( plural locos or locoes )
Etymology: Mexican Spanish, from Spanish, crazy
Date: 1844
1. : locoweed
2. : locoism
III. transitive verb
Date: 1884
1. : to poison with locoweed
2. : to make frenzied or crazy
IV. adjective
Etymology: Spanish
Date: 1887
slang : mentally disordered : crazy , frenzied